Field of the Disclosed Subject Matter
The disclosed subject matter relates to adjustable balloon catheters for treating the luminal systems of a patient. Specifically, the disclosed subject matter relates to catheters having an outer tubular member movable relative to the inner tubular member to define an exposed length of an expandable member.
Description of the Related Art
A variety of catheter devices are known in the art for treating the luminal system of a patient. Of such devices, many are directed to treating vascular systems, including both the cardiovascular system and the peripheral system of a patient. For example, the treatment of the cardiovascular system can include the performance of angioplasty or delivery of balloon-expandable or self-expanding interventional devices (e.g., stents, filters, coils). The treatment of the peripheral system can include, but is not limited to, the treatment of the carotid, popliteal and renal vessels, as well as the venous systems.
One such cardiovascular system treatment includes percutaneous transluminal coronary angioplasty (PTCA); a procedure for treating heart disease. This procedure generally entails introducing a catheter assembly into the cardiovascular system of a patient via the brachial or femoral artery, and advancing the catheter assembly through the coronary vasculature until a balloon portion thereon is positioned across an occlusive lesion. Once in position across the lesion, the balloon is inflated to a predetermined size to radially compress against the atherosclerotic plaque of the lesion to remodel the vessel wall. Subsequently, the balloon is deflated to allow the catheter assembly to be withdrawn from the vasculature.
With treatment of the peripheral system, conventional catheters are configured to treat a specific type of lesion, such as short, long, diffuse, or focal lesions. As such, it is necessary to select in advance the corresponding balloon catheter to treat the lesion of interest. However, conventional catheters are not configured to treat multiple lesions at a single time.
Furthermore, the site of the occlusive lesion can often only be reached by a tortuous pathway through the vasculature of the patient. The difficulty in accessing such regions requires that a successful catheter must be sufficiently flexible longitudinally to follow the tortuous path to the desired site, and at the same time, sufficiently stiff axially to allow the distal end of the catheter to be pushed or otherwise manipulated from an external access location.
To address this problem, catheters having varied flexibility along their length have been developed. For example, each of U.S. Pat. No. 4,782,834 to Maguire and U.S. Pat. No. 5,370,655 to Burns discloses a catheter having sections along its length which are formed from materials having a different stiffness; U.S. Pat. No. 4,976,690 to Solar discloses a catheter having an intermediate waist portion which provides increased flexibility along the catheter shaft; U.S. Pat. No. 5,423,754 to Cornelius discloses a catheter having a greater flexibility at its distal portion due to both a material and dimensional transition in the shaft; and U.S. Pat. No. 5,649,909 to Cornelius discloses a catheter having a proximal portion with greater stiffness due to the application of a polymeric coating thereto.
Such conventional methods and systems generally have been considered satisfactory for their intended purpose. However, there remains a continued need in the art for an improved catheter having varied flexibility to enhance pushability, kink resistance and versatility.
In addition to PTA, PTCA, and atherectomy procedures, commonly, adjustable balloon catheters are used to the peripheral system such as in the venous system or the like. For instance, an adjustable balloon catheter is initially advanced over a guidewire to position the balloon adjacent a stenotic lesion. Once in place, the balloon is then inflated, and the restriction of the vessel is opened. Typically, balloon catheters are structured with a balloon fastened at least at one end to the exterior of a hollow catheter shaft. The hollow interior of the balloon is in a fluid flow relation with the hollow interior of the shaft. Fluid under pressure can thereby be supplied to the interior of the balloon through the shaft in order to expand the balloon against an obstruction. Unlike balloons used for cardiovascular indications, however, balloons for peripheral indications or treatments are generally much longer in length, for example, approximately 220 mm or more.
Catheter balloons typically are of a fixed length and diameter, necessitating the use of different sizes of balloons, for example, to treat vessels of varying diameter and lesions or occlusions of varying lengths.
In addition to the above-described uses of balloon catheters in PTA, PTCA, atherectomy and peripheral system procedures, other balloon catheters can be used to deliver therapeutic drugs or agents. For example, the drug can be coated on the exterior of the balloon. However, such arrangements do not allow for the selections of the desired length or dose of treatment once applied to the surface of the balloon. Furthermore, when such delivery methods are used to deliver a controlled volume of medication to a desired tissue location, the therapeutic agent can be wiped off the surface of the balloon during delivery through the tortuous lumen system or otherwise lost to systemic circulation.
In light of the foregoing, there is a need for an improved balloon catheter having enhanced pushability and crossability, adjustability of the balloon catheter in vivo, and enhanced protectability of any drugs positioned on an expandable member of the balloon catheter. Embodiments of the disclosed subject matter provide solutions for these issues.